Comparison of Conventional Susceptibility Testing, Penicillin-Binding Protein 2a Latex Agglutination Testing, and mecA Real-Time PCR for Det
http://www.100md.com
微生物临床杂志 2005年第7期
University of North Carolina Hospitals and University of North Carolina School of Medicine
Departments of Pathology and Laboratory Medicine
Microbiology, Chapel Hill, North Carolina
ABSTRACT
Penicillin-binding protein (PBP) 2a latex agglutination was compared with conventional susceptibility testing and mecA real-time PCR for the detection of oxacillin resistance in Staphylococcus aureus. Inoculum volume and induction with oxacillin were PBP 2a testing variables. For coagulase-negative Staphylococcus, an increased inoculum volume of 10 μl greatly reduced the number of isolates requiring induction.
TEXT
Staphylococcus aureus and coagulase-negative Staphylococcus (CoNS) are common isolates from positive blood and sterile body fluids (1). At our institution, oxacillin resistance in these organisms is relatively high; 47% of S. aureus and 71% of CoNS isolates are resistant to oxacillin by conventional (phenotype-based) antimicrobial susceptibility testing (AST) (2004 antibiogram; University of North Carolina Hospitals, McLendon Clinical Laboratories). The mecA product, penicillin-binding protein (PBP) 2a, mediates oxacillin resistance. PBP 2a has a lower affinity for beta-lactam antibiotics than do endogenous PBPs of staphylococci, thus allowing peptidoglycan synthesis in the presence of lethal doses of beta-lactams. Due to high rates of oxacillin resistance, empirical vancomycin therapy is rampant. To reduce the unnecessary use of vancomycin, the clinical microbiology laboratory must be able to provide accurate oxacillin susceptibility results with rapid turnaround times. However, the heteroresistant nature of oxacillin resistance in staphylococcal isolates can make detection problematic (3). Disk diffusion and oxacillin screening plate results are occasionally discordant for S. aureus isolates, and resistance detection in CoNS at our institution relies solely on disk diffusion. To improve the performance of phenotype-based susceptibility tests, we sought to evaluate the use of PBP 2a detection in staphylococcal isolates by using mecA real-time PCR as the reference method (11). In addition, the data in the literature vary regarding the necessities of inducing CoNS with oxacillin and of increasing the inoculum volume for the detection of PBP 2a (6-10, 13, 20, 21, 23). This study aims to determine a standard protocol for PBP 2a detection in CoNS that minimizes the time to detection of oxacillin resistance.
(A preliminary report of this work has been presented previously [M. B. Miller, H. Meyer, E. Rogers, and P. H. Gilligan, Abstr. 104th Gen. Meet. Am. Soc. Microbiol., abstr. C-119, 2004].)
Retrospective analysis of significant levels of S. aureus and CoNS isolates from blood and sterile body fluids was evaluated by multiple methods for the detection of oxacillin resistance. In our laboratory, oxacillin resistance in S. aureus is detected phenotypically by the use of Kirby-Bauer disk diffusion in conjunction with an oxacillin screening agar plate containing 6 μg ml–1 oxacillin, whereas oxacillin resistance in CoNS is detected by Kirby-Bauer disk diffusion only. At the time of this study, disk diffusion data were obtained using oxacillin as opposed to cefoxitin to predict oxacillin resistance in Staphylococcus (5, 12, 17). However, isolates that demonstrated discrepant susceptibility results were subsequently tested for cefoxitin susceptibility. Isolates were identified to the genus level with Gram staining and examination of catalase production and colony morphology. Species identification was performed using a tube coagulase test or the BactiStaph latex reagent (Remel, Lenexa, KS) for S. aureus (n = 50) and the bioMerieux APIStaph kit (Marcy l'Etoile, France) for CoNS (n = 100). CoNS species identified included Staphylococcus epidermidis (n = 70), S. hominis (n = 8), species with no identification (n = 8), S. haemolyticus (n = 6), S. lugdunensis (n = 3), S. capitis (n = 3), and S. xylosus (n = 2). The manufacturer's package insert instructions were followed for the PBP 2a latex agglutination test (Slidex methicillin-resistant S. aureus detection kit; bioMerieux, Marcy l'Etoile, France) with the exceptions of those pertaining to inoculum volume and oxacillin induction. Uninduced inocula of 5 μl and 10 μl from a 5% sheep blood agar (SBA) plate, as well as 5 μl and 10 μl of inoculum that had been grown overnight on an SBA plate containing a 1-μg oxacillin disk (Becton Dickinson, Sparks, MD) were used for PBP 2a detection. Colonies were taken directly from an SBA plate, and volumes were measured using 5 loopfuls of a 1-μl calibrated loop or a 10-μl calibrated loop. Cell lysates for PCR were prepared as previously described (14). Real-time PCR was performed on a Roche LightCycler (Roche Diagnostics, Indianapolis, IN) with previously published primers (14) and on a Roche LightCycler FastStart DNA Master SYBR green I kit (Roche Diagnostics, Indianapolis, IN) for amplicon detection.
S. aureus isolates (n = 50) had 100% correlation between PBP 2a detection and mecA PCR when 5 μl of uninduced inoculum was used in the PBP 2a assay. S. aureus isolates used in this study included 56% (n = 28) that were oxacillin resistant. In addition, the PBP 2a and mecA results were identical to phenotypic AST data from these isolates. Although a relatively small number of S. aureus isolates were characterized, these data are consistent with previous reports for the use of PBP 2a in S. aureus (2, 11, 15, 16, 18, 19, 22). None of the S. aureus isolates tested required increased inoculum volume or induction by oxacillin for the detection of PBP 2a. However, S. aureus strains requiring oxacillin-cefoxitin induction for PBP 2a detection have been reported (15, 16, 20).
Although the CoNS isolates (n = 100) also demonstrated 100% correlation between PBP 2a and mecA testing, 5 μl of uninduced inoculum in the PBP 2a assay detected only 42% (n = 30) of mecA-positive isolates (n = 71). For PBP 2a detection in CoNS, the induced 5-μl inoculum performed optimally and demonstrated 100% sensitivity and specificity relative to PCR. However, increasing the uninduced inoculum to 10 μl allowed for the detection of 97% (n = 69) of mecA-positive isolates by the PBP 2a test. Only 3% (n = 2) of mecA-positive isolates required induction for detection of PBP 2a by latex agglutination.
The use of 10-μl inocula of CoNS did not result in false positives, and therefore, these inocula could be used to detect PBP 2a in CoNS without induction. Thus, for detection of mecA-mediated oxacillin resistance in CoNS, the laboratory could use a 10-μl inoculum and have positive results within 20 min of obtaining an isolate. However, negative results obtained upon initial testing should be followed up with overnight oxacillin induction to prevent false negatives. It should be noted that the use of 10-μl inocula of S. aureus resulted in a 14% false-positivity rate due to increased interpretation variability, and this method is not recommended for S. aureus.
There were three very major errors and six major errors in our conventional AST reporting (oxacillin disk diffusion) for CoNS when using PBP 2a/mecA testing as the reference method. These data did not show a correlation between species of CoNS and the reporting of very major or major errors in conventional AST. Subsequent testing by cefoxitin disk diffusion showed that eight reporting errors would have been avoided by the use of cefoxitin to predict oxacillin resistance. One very major error still occurred by cefoxitin disk diffusion; resistance in this isolate was detected in the PBP 2a agglutination assay using an uninduced 10-μl inoculum.
Although the use of cefoxitin disk diffusion increases the accuracy of S. aureus and CoNS conventional AST, testing still requires 24 h after colony formation. PBP 2a latex agglutination can be performed in 20 min with minimal technical training. The use of PBP 2a detection for staphylococci allows for accurate same-day results for all S. aureus and oxacillin-resistant CoNS isolates. This can be achieved by increasing the inoculum size to 10 μl for CoNS isolates and limiting induction-dependent testing to PBP 2a-negative CoNS isolates. A 3% false-negative rate for PBP 2a detection in CoNS without induction precludes the use of this test as a "rapid" means for oxacillin resistance detection in CoNS, as overnight incubation is required for the induction step. However, simply placing an oxacillin disk on subculture medium from positive blood cultures with a Gram stain consistent with the presence of staphylococci would eliminate the delay associated with induction testing (8). In addition, several reports have demonstrated the use of the PBP 2a latex agglutination method directly from positive blood cultures; however, the sensitivities and specificities of these procedures vary significantly (4; T. Yamazumi, I. Furuta, T. Maeno, Y. Tsubakimoto, and M. A. Pfaller, Abstr. 102nd Gen. Meet. Am. Soc. Microbiol., abstr. C-99, 2002; L. A. Bassiwa and D. Craft, Abstr. 103rd Gen. Meet. Am. Soc. Microbiol., abstr. C-86, 2003). Decreasing the turnaround time for the detection of oxacillin resistance in critical cultures such as those for blood and sterile fluids will allow physicians to initiate or change a patient's antimicrobial regimen more appropriately and perhaps prevent the overuse of vancomycin.
ACKNOWLEDGMENTS
We gratefully acknowledge Larry Donahoe and Steve Rothenberg at bioMerieux for reagent and protocol support.
REFERENCES
Bannerman, T. L. 2003. Staphylococcus, Micrococcus, and other catalase-positive cocci that grow aerobically, p. 384-404. In E. J. Baron, J. H. Jorgensen, M. A. Pfaller, and R. H. Yolken (ed.), Manual of clinical microbiology, 8th ed., vol. 1. ASM Press, Washington, D.C.
Cavassini, M., A. Wenger, K. Jaton, D. S. Blanc, and J. Bille. 1999. Evaluation of MRSA-Screen, a simple anti-PBP 2a slide latex agglutination kit, for rapid detection of methicillin resistance in Staphylococcus aureus. J. Clin. Microbiol. 37:1591-1594.
Chambers, H. F. 1997. Methicillin resistance in staphylococci: molecular and biochemical basis and clinical implications. Clin. Microbiol. Rev. 10:781-791.
Chapin, K. C., and M. C. Musgnug. 2004. Evaluation of penicillin binding protein 2a latex agglutination assay for identification of methicillin-resistant Staphylococcus aureus directly from blood cultures. J. Clin. Microbiol. 42:1283-1284.
Felten, A., B. Grandry, P. H. Lagrange, and I. Casin. 2002. Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test. J. Clin. Microbiol. 40:2766-2771.
Horstkotte, M. A., J. K. Knobloch, H. Rohde, and D. Mack. 2001. Rapid detection of methicillin resistance in coagulase-negative staphylococci by a penicillin-binding protein 2a-specific latex agglutination test. J. Clin. Microbiol. 39:3700-3702.
Hussain, Z., L. Stoakes, S. Garrow, S. Longo, V. Fitzgerald, and R. Lannigan. 2000. Rapid detection of mecA-positive and mecA-negative coagulase-negative staphylococci by an anti-penicillin binding protein 2a slide latex agglutination test. J. Clin. Microbiol. 38:2051-2054.
Hussain, Z., L. Stoakes, M. A. John, S. Garrow, and V. Fitzgerald. 2002. Detection of methicillin resistance in primary blood culture isolates of coagulase-negative staphylococci by PCR, slide agglutination, disk diffusion, and a commercial method. J. Clin. Microbiol. 40:2251-2253.
Louie, L., A. Majury, J. Goodfellow, M. Louie, and A. E. Simor. 2001. Evaluation of a latex agglutination test (MRSA-Screen) for detection of oxacillin resistance in coagulase-negative staphylococci. J. Clin. Microbiol. 39:4149-4151.
Marriott, D. J. E., T. Karagiannis, J. L. Harkness, and P. Kearney. 1996. Further evaluation of the MRSA-Screen kit for rapid detection of methicillin resistance. J. Clin. Microbiol. 37:3783-3784.
Nakatomi, Y., and J. Sugiyama. 1998. A rapid latex agglutination assay for the detection of penicillin-binding protein 2'. Microbiol. Immunol. 42:739-743.
NCCLS. 2004. Performance standards for antimicrobial susceptibility testing; fourteenth informational supplement, vol. 24, p. 42-43. M100-S14. National Committee for Clinical Laboratory Standards, Wayne, Pa.
Petinaki, E., V. Miriagou, L. S. Tzouvelekis, F. Hatzi, N. J. Legakis, and A. N. Maniatis. 2002. Evaluation of an anti-PBP 2a slide latex agglutination test in coagulase-negative staphylococci isolated in Greek hospitals. Diagn. Microbiol. Infect. Dis. 42:279-282.
Reischl, U., H. J. Linde, M. Metz, B. Leppmeier, and N. Lehn. 2000. Rapid identification of methicillin-resistant Staphylococcus aureus and simultaneous species confirmation using real-time fluorescence PCR. J. Clin. Microbiol. 38:2429-2433.
Rohrer, S., M. Tschierske, R. Zbinden, and B. Berger-Bachi. 2001. Improved methods for detection of methicillin-resistant Staphylococcus aureus. Eur. J. Clin. Microbiol. Infect. Dis. 20:267-270.
Sakoulas, G., H. S. Gold, L. Venkataraman, P. C. DeGirolami, G. M. Eliopoulos, and Q. Qian. 2001. Methicillin-resistant Staphylococcus aureus: comparison of susceptibility testing methods and analysis of mecA-positive susceptible strains. J. Clin. Microbiol. 39:3946-3951.
Skov, R., R. Smyth, M. Clausen, A. R. Larsen, N. Frimodt-Moller, B. Olsson-Liljequist, and G. Kahlmeter. 2003. Evaluation of a cefoxitin 30 microgram disc on Iso-Sensitest agar for detection of methicillin-resistant Staphylococcus aureus. J. Antimicrob. Chemother. 52:204-207.
Udo, E. E., E. M. Mokadas, A. Al-Haddad, B. Mathew, L. E. Jacob, and S. C. Sanyal. 2000. Rapid detection of methicillin resistance in staphylococci using a slide latex agglutination kit. Int. J. Antimicrob. Agents 15:19-24.
van Griethuysen, A., M. Pouw, N. van Leeuwen, M. Heck, P. Willemse, A. Buiting, and J. Kluytmans. 1999. Rapid slide latex agglutination test for detection of methicillin resistance in Staphylococcus aureus. J. Clin. Microbiol. 37:2789-2792.
van Leeuwen, W. B., C. van Pelt, A. Luijendijk, H. A. Verbrugh, and W. H. Goessens. 1999. Rapid detection of methicillin resistance in Staphylococcus aureus isolates by the MRSA-Screen latex agglutination test. J. Clin. Microbiol. 37:3029-3030.
Yamazumi, T., I. Furuta, D. J. Diekema, M. A. Pfaller, and R. N. Jones. 2001. Comparison of the Vitek gram-positive susceptibility 106 card, the MRSA-Screen latex agglutination test, and mecA analysis for detecting oxacillin resistance in a geographically diverse collection of clinical isolates of coagulase-negative staphylococci. J. Clin. Microbiol. 39:3633-3636.
Yamazumi, T., S. A. Marshall, W. W. Wilke, D. J. Diekema, M. A. Pfaller, and R. N. Jones. 2001. Comparison of the Vitek Gram-Positive Susceptibility 106 card and the MRSA-Screen latex agglutination test for determining oxacillin resistance in clinical bloodstream isolates of Staphylococcus aureus. J. Clin. Microbiol. 39:53-56.
Zbinden, R., M. Ritzler, E. Ritzler, and B. Berger-Bachi. 2001. Detection of penicillin-binding protein 2a by rapid slide latex agglutination test in coagulase-negative staphylococci. J. Clin. Microbiol. 39:412.(Melissa B. Miller, Heathe)
Departments of Pathology and Laboratory Medicine
Microbiology, Chapel Hill, North Carolina
ABSTRACT
Penicillin-binding protein (PBP) 2a latex agglutination was compared with conventional susceptibility testing and mecA real-time PCR for the detection of oxacillin resistance in Staphylococcus aureus. Inoculum volume and induction with oxacillin were PBP 2a testing variables. For coagulase-negative Staphylococcus, an increased inoculum volume of 10 μl greatly reduced the number of isolates requiring induction.
TEXT
Staphylococcus aureus and coagulase-negative Staphylococcus (CoNS) are common isolates from positive blood and sterile body fluids (1). At our institution, oxacillin resistance in these organisms is relatively high; 47% of S. aureus and 71% of CoNS isolates are resistant to oxacillin by conventional (phenotype-based) antimicrobial susceptibility testing (AST) (2004 antibiogram; University of North Carolina Hospitals, McLendon Clinical Laboratories). The mecA product, penicillin-binding protein (PBP) 2a, mediates oxacillin resistance. PBP 2a has a lower affinity for beta-lactam antibiotics than do endogenous PBPs of staphylococci, thus allowing peptidoglycan synthesis in the presence of lethal doses of beta-lactams. Due to high rates of oxacillin resistance, empirical vancomycin therapy is rampant. To reduce the unnecessary use of vancomycin, the clinical microbiology laboratory must be able to provide accurate oxacillin susceptibility results with rapid turnaround times. However, the heteroresistant nature of oxacillin resistance in staphylococcal isolates can make detection problematic (3). Disk diffusion and oxacillin screening plate results are occasionally discordant for S. aureus isolates, and resistance detection in CoNS at our institution relies solely on disk diffusion. To improve the performance of phenotype-based susceptibility tests, we sought to evaluate the use of PBP 2a detection in staphylococcal isolates by using mecA real-time PCR as the reference method (11). In addition, the data in the literature vary regarding the necessities of inducing CoNS with oxacillin and of increasing the inoculum volume for the detection of PBP 2a (6-10, 13, 20, 21, 23). This study aims to determine a standard protocol for PBP 2a detection in CoNS that minimizes the time to detection of oxacillin resistance.
(A preliminary report of this work has been presented previously [M. B. Miller, H. Meyer, E. Rogers, and P. H. Gilligan, Abstr. 104th Gen. Meet. Am. Soc. Microbiol., abstr. C-119, 2004].)
Retrospective analysis of significant levels of S. aureus and CoNS isolates from blood and sterile body fluids was evaluated by multiple methods for the detection of oxacillin resistance. In our laboratory, oxacillin resistance in S. aureus is detected phenotypically by the use of Kirby-Bauer disk diffusion in conjunction with an oxacillin screening agar plate containing 6 μg ml–1 oxacillin, whereas oxacillin resistance in CoNS is detected by Kirby-Bauer disk diffusion only. At the time of this study, disk diffusion data were obtained using oxacillin as opposed to cefoxitin to predict oxacillin resistance in Staphylococcus (5, 12, 17). However, isolates that demonstrated discrepant susceptibility results were subsequently tested for cefoxitin susceptibility. Isolates were identified to the genus level with Gram staining and examination of catalase production and colony morphology. Species identification was performed using a tube coagulase test or the BactiStaph latex reagent (Remel, Lenexa, KS) for S. aureus (n = 50) and the bioMerieux APIStaph kit (Marcy l'Etoile, France) for CoNS (n = 100). CoNS species identified included Staphylococcus epidermidis (n = 70), S. hominis (n = 8), species with no identification (n = 8), S. haemolyticus (n = 6), S. lugdunensis (n = 3), S. capitis (n = 3), and S. xylosus (n = 2). The manufacturer's package insert instructions were followed for the PBP 2a latex agglutination test (Slidex methicillin-resistant S. aureus detection kit; bioMerieux, Marcy l'Etoile, France) with the exceptions of those pertaining to inoculum volume and oxacillin induction. Uninduced inocula of 5 μl and 10 μl from a 5% sheep blood agar (SBA) plate, as well as 5 μl and 10 μl of inoculum that had been grown overnight on an SBA plate containing a 1-μg oxacillin disk (Becton Dickinson, Sparks, MD) were used for PBP 2a detection. Colonies were taken directly from an SBA plate, and volumes were measured using 5 loopfuls of a 1-μl calibrated loop or a 10-μl calibrated loop. Cell lysates for PCR were prepared as previously described (14). Real-time PCR was performed on a Roche LightCycler (Roche Diagnostics, Indianapolis, IN) with previously published primers (14) and on a Roche LightCycler FastStart DNA Master SYBR green I kit (Roche Diagnostics, Indianapolis, IN) for amplicon detection.
S. aureus isolates (n = 50) had 100% correlation between PBP 2a detection and mecA PCR when 5 μl of uninduced inoculum was used in the PBP 2a assay. S. aureus isolates used in this study included 56% (n = 28) that were oxacillin resistant. In addition, the PBP 2a and mecA results were identical to phenotypic AST data from these isolates. Although a relatively small number of S. aureus isolates were characterized, these data are consistent with previous reports for the use of PBP 2a in S. aureus (2, 11, 15, 16, 18, 19, 22). None of the S. aureus isolates tested required increased inoculum volume or induction by oxacillin for the detection of PBP 2a. However, S. aureus strains requiring oxacillin-cefoxitin induction for PBP 2a detection have been reported (15, 16, 20).
Although the CoNS isolates (n = 100) also demonstrated 100% correlation between PBP 2a and mecA testing, 5 μl of uninduced inoculum in the PBP 2a assay detected only 42% (n = 30) of mecA-positive isolates (n = 71). For PBP 2a detection in CoNS, the induced 5-μl inoculum performed optimally and demonstrated 100% sensitivity and specificity relative to PCR. However, increasing the uninduced inoculum to 10 μl allowed for the detection of 97% (n = 69) of mecA-positive isolates by the PBP 2a test. Only 3% (n = 2) of mecA-positive isolates required induction for detection of PBP 2a by latex agglutination.
The use of 10-μl inocula of CoNS did not result in false positives, and therefore, these inocula could be used to detect PBP 2a in CoNS without induction. Thus, for detection of mecA-mediated oxacillin resistance in CoNS, the laboratory could use a 10-μl inoculum and have positive results within 20 min of obtaining an isolate. However, negative results obtained upon initial testing should be followed up with overnight oxacillin induction to prevent false negatives. It should be noted that the use of 10-μl inocula of S. aureus resulted in a 14% false-positivity rate due to increased interpretation variability, and this method is not recommended for S. aureus.
There were three very major errors and six major errors in our conventional AST reporting (oxacillin disk diffusion) for CoNS when using PBP 2a/mecA testing as the reference method. These data did not show a correlation between species of CoNS and the reporting of very major or major errors in conventional AST. Subsequent testing by cefoxitin disk diffusion showed that eight reporting errors would have been avoided by the use of cefoxitin to predict oxacillin resistance. One very major error still occurred by cefoxitin disk diffusion; resistance in this isolate was detected in the PBP 2a agglutination assay using an uninduced 10-μl inoculum.
Although the use of cefoxitin disk diffusion increases the accuracy of S. aureus and CoNS conventional AST, testing still requires 24 h after colony formation. PBP 2a latex agglutination can be performed in 20 min with minimal technical training. The use of PBP 2a detection for staphylococci allows for accurate same-day results for all S. aureus and oxacillin-resistant CoNS isolates. This can be achieved by increasing the inoculum size to 10 μl for CoNS isolates and limiting induction-dependent testing to PBP 2a-negative CoNS isolates. A 3% false-negative rate for PBP 2a detection in CoNS without induction precludes the use of this test as a "rapid" means for oxacillin resistance detection in CoNS, as overnight incubation is required for the induction step. However, simply placing an oxacillin disk on subculture medium from positive blood cultures with a Gram stain consistent with the presence of staphylococci would eliminate the delay associated with induction testing (8). In addition, several reports have demonstrated the use of the PBP 2a latex agglutination method directly from positive blood cultures; however, the sensitivities and specificities of these procedures vary significantly (4; T. Yamazumi, I. Furuta, T. Maeno, Y. Tsubakimoto, and M. A. Pfaller, Abstr. 102nd Gen. Meet. Am. Soc. Microbiol., abstr. C-99, 2002; L. A. Bassiwa and D. Craft, Abstr. 103rd Gen. Meet. Am. Soc. Microbiol., abstr. C-86, 2003). Decreasing the turnaround time for the detection of oxacillin resistance in critical cultures such as those for blood and sterile fluids will allow physicians to initiate or change a patient's antimicrobial regimen more appropriately and perhaps prevent the overuse of vancomycin.
ACKNOWLEDGMENTS
We gratefully acknowledge Larry Donahoe and Steve Rothenberg at bioMerieux for reagent and protocol support.
REFERENCES
Bannerman, T. L. 2003. Staphylococcus, Micrococcus, and other catalase-positive cocci that grow aerobically, p. 384-404. In E. J. Baron, J. H. Jorgensen, M. A. Pfaller, and R. H. Yolken (ed.), Manual of clinical microbiology, 8th ed., vol. 1. ASM Press, Washington, D.C.
Cavassini, M., A. Wenger, K. Jaton, D. S. Blanc, and J. Bille. 1999. Evaluation of MRSA-Screen, a simple anti-PBP 2a slide latex agglutination kit, for rapid detection of methicillin resistance in Staphylococcus aureus. J. Clin. Microbiol. 37:1591-1594.
Chambers, H. F. 1997. Methicillin resistance in staphylococci: molecular and biochemical basis and clinical implications. Clin. Microbiol. Rev. 10:781-791.
Chapin, K. C., and M. C. Musgnug. 2004. Evaluation of penicillin binding protein 2a latex agglutination assay for identification of methicillin-resistant Staphylococcus aureus directly from blood cultures. J. Clin. Microbiol. 42:1283-1284.
Felten, A., B. Grandry, P. H. Lagrange, and I. Casin. 2002. Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test. J. Clin. Microbiol. 40:2766-2771.
Horstkotte, M. A., J. K. Knobloch, H. Rohde, and D. Mack. 2001. Rapid detection of methicillin resistance in coagulase-negative staphylococci by a penicillin-binding protein 2a-specific latex agglutination test. J. Clin. Microbiol. 39:3700-3702.
Hussain, Z., L. Stoakes, S. Garrow, S. Longo, V. Fitzgerald, and R. Lannigan. 2000. Rapid detection of mecA-positive and mecA-negative coagulase-negative staphylococci by an anti-penicillin binding protein 2a slide latex agglutination test. J. Clin. Microbiol. 38:2051-2054.
Hussain, Z., L. Stoakes, M. A. John, S. Garrow, and V. Fitzgerald. 2002. Detection of methicillin resistance in primary blood culture isolates of coagulase-negative staphylococci by PCR, slide agglutination, disk diffusion, and a commercial method. J. Clin. Microbiol. 40:2251-2253.
Louie, L., A. Majury, J. Goodfellow, M. Louie, and A. E. Simor. 2001. Evaluation of a latex agglutination test (MRSA-Screen) for detection of oxacillin resistance in coagulase-negative staphylococci. J. Clin. Microbiol. 39:4149-4151.
Marriott, D. J. E., T. Karagiannis, J. L. Harkness, and P. Kearney. 1996. Further evaluation of the MRSA-Screen kit for rapid detection of methicillin resistance. J. Clin. Microbiol. 37:3783-3784.
Nakatomi, Y., and J. Sugiyama. 1998. A rapid latex agglutination assay for the detection of penicillin-binding protein 2'. Microbiol. Immunol. 42:739-743.
NCCLS. 2004. Performance standards for antimicrobial susceptibility testing; fourteenth informational supplement, vol. 24, p. 42-43. M100-S14. National Committee for Clinical Laboratory Standards, Wayne, Pa.
Petinaki, E., V. Miriagou, L. S. Tzouvelekis, F. Hatzi, N. J. Legakis, and A. N. Maniatis. 2002. Evaluation of an anti-PBP 2a slide latex agglutination test in coagulase-negative staphylococci isolated in Greek hospitals. Diagn. Microbiol. Infect. Dis. 42:279-282.
Reischl, U., H. J. Linde, M. Metz, B. Leppmeier, and N. Lehn. 2000. Rapid identification of methicillin-resistant Staphylococcus aureus and simultaneous species confirmation using real-time fluorescence PCR. J. Clin. Microbiol. 38:2429-2433.
Rohrer, S., M. Tschierske, R. Zbinden, and B. Berger-Bachi. 2001. Improved methods for detection of methicillin-resistant Staphylococcus aureus. Eur. J. Clin. Microbiol. Infect. Dis. 20:267-270.
Sakoulas, G., H. S. Gold, L. Venkataraman, P. C. DeGirolami, G. M. Eliopoulos, and Q. Qian. 2001. Methicillin-resistant Staphylococcus aureus: comparison of susceptibility testing methods and analysis of mecA-positive susceptible strains. J. Clin. Microbiol. 39:3946-3951.
Skov, R., R. Smyth, M. Clausen, A. R. Larsen, N. Frimodt-Moller, B. Olsson-Liljequist, and G. Kahlmeter. 2003. Evaluation of a cefoxitin 30 microgram disc on Iso-Sensitest agar for detection of methicillin-resistant Staphylococcus aureus. J. Antimicrob. Chemother. 52:204-207.
Udo, E. E., E. M. Mokadas, A. Al-Haddad, B. Mathew, L. E. Jacob, and S. C. Sanyal. 2000. Rapid detection of methicillin resistance in staphylococci using a slide latex agglutination kit. Int. J. Antimicrob. Agents 15:19-24.
van Griethuysen, A., M. Pouw, N. van Leeuwen, M. Heck, P. Willemse, A. Buiting, and J. Kluytmans. 1999. Rapid slide latex agglutination test for detection of methicillin resistance in Staphylococcus aureus. J. Clin. Microbiol. 37:2789-2792.
van Leeuwen, W. B., C. van Pelt, A. Luijendijk, H. A. Verbrugh, and W. H. Goessens. 1999. Rapid detection of methicillin resistance in Staphylococcus aureus isolates by the MRSA-Screen latex agglutination test. J. Clin. Microbiol. 37:3029-3030.
Yamazumi, T., I. Furuta, D. J. Diekema, M. A. Pfaller, and R. N. Jones. 2001. Comparison of the Vitek gram-positive susceptibility 106 card, the MRSA-Screen latex agglutination test, and mecA analysis for detecting oxacillin resistance in a geographically diverse collection of clinical isolates of coagulase-negative staphylococci. J. Clin. Microbiol. 39:3633-3636.
Yamazumi, T., S. A. Marshall, W. W. Wilke, D. J. Diekema, M. A. Pfaller, and R. N. Jones. 2001. Comparison of the Vitek Gram-Positive Susceptibility 106 card and the MRSA-Screen latex agglutination test for determining oxacillin resistance in clinical bloodstream isolates of Staphylococcus aureus. J. Clin. Microbiol. 39:53-56.
Zbinden, R., M. Ritzler, E. Ritzler, and B. Berger-Bachi. 2001. Detection of penicillin-binding protein 2a by rapid slide latex agglutination test in coagulase-negative staphylococci. J. Clin. Microbiol. 39:412.(Melissa B. Miller, Heathe)